The three primary colors, RGB (Red, Green and Blue) of an image display using organic EL elements have been produced by a method of evaporating color materials through a metal mask (hereafter, called the mask evaporation method) as described in “9th International workshop on Inorganic and organic electroluminescence, p. 137 (1998)” or by a method of applying the ink jet printing (hereafter, called the ink jet method) as described in “Extended Abstract of EL98, 147 (1998)”. However, it is difficult to produce large-area and high-resolution screens for future demand by these conventional methods.
For example, in the mask evaporation method it is hard to make a thin mask of several tens of μm in close contact with a large substrate without wrinkle or folds and to remove the effect of thermal expansion in the evaporation of metal electrodes. Therefore, it is difficult to realize large area, high-resolution screens. In addition, the ink jet method is inappropriate for printing sufficiently wide and high-resolution light-emitting regions because of its low deposition-positioning precision.
Thus, as a method capable of solving these problems, there has been proposed a method of transferring dye materials onto a substrate so that the transfer layer and the transferred layer can be kept in close contact with each other without use of liquid solution. In this method, as described in “Society of Information Display '00, p. 1080 (2000)”, a pattern of three primaries RGB is formed by screen-printing on a transfer substrate from which the dye materials are to be transferred, and the three-primary materials are thermally transferred to the transferred substrate at a time.
In this transfer technique, however, a dye pattern is formed by the screen printing method using a solution, and thus it is difficult to produce a large-area and high-resolution pattern that is to be transferred. In addition, since three-color dye materials are transferred at a time, a long transfer time of tens of minutes must be taken in order for the transfer speeds of the color materials to be adjusted.